Material handling apparatus



Dec. 1, 1959 Filed July 5, 1956 H. A. COTESWORTH ETAL MATERIAL HANDLINGAPPARATUS 4 Sheets-Sheet 1 NVENTO S 447 14. OTESWORI'H Dec. 1, 1959 H,OTESWRTH EI'AL 2,915,332

MATERIAL HANDLING APPARATUS 4 Sheets-Sheet 2 Filed July 3, 1956 r 4 l I1 INVENTORS #404) A Gore-swam flwwwms Arr-w? era a; if

4 Sheets-Sheet 3 Filed July 3, 1956 INVENTORS M 6 Wm WN a E L Q @J w W ZPM. MM Y I B 1959 H. A. COTESWORTH ETAL 2,915,332 MATERIAL HANDLINGAPPARATUS 4 Sheets-Sheet 4 Filed July 3, 1956 INVEN TORS Maker 4-Care-swear FA'PA/WUN I4. flaw/ {,4 Nays United States Patent MATERIALHANDLING APPARATUS Harry A. Cotesworth, Cleveland Heights, and FranklinW. Dunning, Painesville, Ohio, assignors to The Cleveland Crane &Engineering Company, Wicklifie, Ohio, a corporation of Ohio ApplicationJuly 3, 1956, Serial No. 595,692

3 Claims. (Cl. 294-88) The present invention relates to a materialhandling apparatus and, more particularly, to an apparatus including anoverhead movable support having suspended therefrom a grab for handlingthe load, particularly cylindrical articles such as a roll of paper, thegrab, preferably, being adapted to rotate or pivot the load beinghandled about a generally horizontal axis.

One of the objects of the present invention is the provision of a newand improved material handling apparatus including a support member, oroverhead carrier, having suspended therefrom a grab for handling theload, which grab includes pivoted clamp arms and is particularlysuitable for handling cylindrical objects such as rolls of paper byclamping against the curved sides thereof and is constructed andarranged so that articles of different size may be securely handledwithout modifying the device and so that the articles may be rotatedendwise.

Another object of the present invention is the provision of a new andimproved material handling apparatus including a support member, oroverhead carrier, having suspended therefrom a grab for handling theload, which grab device includes pivoted clamp arms movable about theirpivots to move oppositely disposed one ends thereof toward each other toclamp a load therebetween, power means including a pump and drivingmotor therefor supported on the grab, and a fluid pressure actuatoroperatively connected between the ends of arms remote from theload-clamping ends, the operation of the driving motor for the pump andthe actuator being controlled from a position remote from the grab.

Another object of the present invention is the provision of a new andimproved grab for handling material and having a pivoted arm and aload-engaging member on one end of the arm engageable with the load uponmovement of the arm about its pivot, the member being supported on thearm for self aligning movement about a plurality of axes to enable themember to properly engage the article being handled.

Another object of the present invention is the provision of a new andimproved overhead suspended grab device having a load-engaging shoesupported for aligning movement about a horizontal axis on engagementwith the load, the grab being so constructed and arranged that themember has a large range of aligning movement about the horizontal axisbut yet will not tilt to a position, when not in engagement with theload, which will prevent the aligning movement from occurring uponengagement with the load.

A further object of the present invention is the provision of a new andimproved material handling apparatus having a pair of oppositelydisposed loadengaging elements rotatably supported by different ones ofa pair of pivoted arms movable about their pivots to move the memberstoward and away from each other and double-acting hydraulic actuatorsfor rotating the loadengaging members, the connections of the actuatorto the fluid under pressure and reservoir return system being soarranged that the load-engaging'elements are held in 2,915,332 PatentedDec. 1,1959

their immediate positions upon the closing of the fluid pressure supplyconnection thereto, or on the-loss of pressure in the supply system byfluid pressure within the actuators.

A still further object of the present invention is the provision of anew and improved material handling apparatus including a grab devicehaving a double-acting hydraulic cylinder and cooperating pistonconnected between corresponding ends of a pair of pivoted clamp arms andoperable upon the supply of pressure to a first side thereof to move thearms about their pivot and apply a clamping pressure to the load andupon supply of fluid pressure to the other side to move the arms in theopposite direction about their pivots and release the clamping pressure,the hydraulic system being so arranged that the presure fluid cannot beexhausted from the first side of the cylinder until pressure fluid issupplied to the other side.

The invention resides in certain constructions, combinations, andarrangements of parts, and further objects and advantages will beapparent to those skilled in the art to which it relates from thefollowing description of the preferred embodiment described withreference to the accompanying drawings forming a part of thisspecification, in which:

Fig. l is an elevational view of an overhead-supported material handlingapparatus embodying the present invention;

Fig. 2 is an enlarged elevational view of the material manipulatingdevice or grab of the apparatus shown in Fig. 1;

Fig. 3 is a plan view of the device shown in Fig. 2;

Fig. 4 is an enlarged fragmentary side elevational view of the materialmanipulating device or graph shown in Fig. 2;

Pig. 5 is a horizontal sectional view taken approximately along line 55of Fig. 2;

Fig. 6 is a fragmentary. sectional view taken approximately along line66 of Fig. 4;

Fig. 7 is a fragmentary sectional view taken mately along line 77 ofFig. 4; and

Fig. 8 is a diagrammatic view of the fluid presure circuit of theapparatus shown in the drawings. 1

While the present invention is susceptible of various constructions andof use in various applications, it is herein shown as embodied in amaterial handling apparatus supported for overhead movement by anoverhead rail 10 and particularly adapted for handling cylindricalarticles such as rolls of paper. The material handling apparatuscomprises a carrier 11 having a material manipulating, or grab, device12 suspended therefrom. The carrier 11 includes a frame 13 supportedfrom front and rear trucks 14 each having wheels 15 which ride on ahorizontal flange 16 of the overhead rail 10. The trucks 14 have motorsl7 thereon for driving one of the wheels of each truck to move thecarriers 11 along the rail 10. The motors 17 and the grab device 12 arecontrolled from an operators cab 18 depending from the frame member 13at one end thereof. The material manipulating, or grab device 12, issuspended from the frame 13 by cables 20, 21 which are taken in or letout to raise approxior lower the grab 12 by motor-driven mechanism 22 indetail and it will be understood that other suitable mechanism forsupporting the grab device 12 may be substituted for that shown.

The grab device 12, in the illustrated embodiment, is

particularly suitable for handling cylindrical articles, particularlyrolls of paper, and, preferably, comprises a pair of generally verticalclamp arms 25, 26 pivotally connected to the opposite ends of ahorizontal frame member 27 suspended from the carrier 11 by the cables20, 21 which pass about spaced sheaves'28, 29 mounted on the horizontalframe member27. The clamp arms are pivoted to the member 27 at a pointintermediate the ends .of each of the clamp arms by pivot pins 31 andare supported by the pins 31 for movement in a common plane and aboutparallel axes. Each of the clamp arms has a load-engaging element 33supported on the lower end thereof for engaging the load to be handledwhen the clamp arms 25, 26 are moved about their pivots in a clampdirection.

The clamp arms 25, 26 and the load-engaging elements thereon are of thesame construction and, therefore, only the clamp arm 26 will bedescribed in detail, the reference numerals, however, for the parts ofthe clamp arm 26 and the load-engaging element 33 thereon will beapplied to the corresponding parts of the clamp arm and itsload-engaging element 33. r

The clamp arm 26 is formed by spaced side plates 35 joined by inner andouter transverse plates 36 to form a rectangularly shaped member. Arectangular block 37 is supported between the lower ends of the plates35 by hearing pins 38, 39 received in a bore 41 in the block 37. Thepins 38, 39 extend from the opposite ends of the bore 41 through theadjacent plates 35. The outer sides of each of the plates 35 have acircular bearing block 43 secured thereto opposite the block 37. Thepins 38, 39 pass through the adjacent bearing block 43 and each areprevented from rotation by a keeper plate 44 bolted or otherwisesecured, preferably detachably, to the outer side of the adjacent block43 and extending into a notch 45 in theadjacent pin. The bore 41 ispreferably of such a diameter to permit the positioning of suitablebearings intermediate the pins 38, 39 and the side wall of the bore 41.The described construction permits the block 37 to rotate about the axisof pins 38, 39, which axis is parallel to the axis of the pin 31pivotally securing the clamp arm 26 to the member 27.

The bore 41 is intersected by a transverse bore 47 extending between theinner and outer sides of the block 37. A trunnion pin 48 is positionedin the bore 47 and extends outwardly of the block 37 at each endthereof, the portion 49 of the trunnionpin 48 extending outwardly fromthe outer side of the block 37, i.e. the side facing the clamp arm 25being of greater extent than the portion 50 extendingvfrom the otherside of the block. The portion 50 of the trunnion pin 48 has a lock nut51 thereon to prevent the pin 48 from moving outwardly of the block 37.It will be noted that the pins 38, 39 terminate short of each other andthat the space between the pins is such as to permit the passage of thetrunnion pin 48.

The load engaging element 33 is rotatably supported on the outer portion49 of the trunnion pin 48 and comprises a pair of elongated shoes 55supported in parallel relationship and having load-engaging faces shapedto conform to the configuration of the load to be handled. In theillustrated embodiment, the shoes 55 have concave faces curved about anaxis parallel to the length of the shoes and adapted to conform to thecylindrical configuration of a paper roll 56 to be handled by theapparatus. The shoes are horizontally spaced from each other and engagethe circumference of the paper roll 56 along spaced lines which extendaxially of the paper roll. The shoes 55 are joined by a member 58connected to the shoes 55 at approximately the midpoint of the side ofthe shoes opposite the load-engagingfaces. As is best shown in Fig. 6,the shoes 55 are each connected to the member 58 by a pin 60 whichpasses through the member 58 and through transverse ribs 61, '62 of theshoe, the ribs 61, 62 being positioned on opposite sides of the member58. When the shoes 55 are in the vertical Q position shown in thedrawing with the member 58 substantially horizontal, the ribs 61 of theshoes are upper ribs and the ribs 62 are lower ribs. The pins extendoutwardly of the ribs 61, 62 through which they pass and each of theribs 62 has a keeper plate 63 bolted thereto which, in turn, has an edgereceived in a notch 64 in the adjacent pin 60. The keeper plate 63prevents rotation of the pin 60 engaged thereby with respect to the shoe55 supporting the pin. The pins 60, however, are rotatable with respectto the member 58. The described construction permits the shoes 55 torotate a limited amount about the axis of the corresponding pin 60 topermit the load-engaging faces of the shoes 55 to align themselves aboutan axis extending parallel to the axis of the roll of paper beinghandled and contained in a plane perpendicular to the axis of trunnionpin 48. The shoes 55 are biased in an outward direction with respect toeach other by a spring 65 connected between the keeper plates 63. Themember 58 has a bore 66 therein which opens into the side of the memberopposite the shoes 55 and which receives the trunnion pin 48. The bore66 is preferably of such a diameter to permit suitable antifrictionmeans to be interposed between the trunnion pin 48 and the wall of thebore 66. A thrust bearing 68 is preferably provided intermediate themember 58 and the block 37. The load-engaging element 33 is rotatable onthe trunnion pin 48 to permit the paper roll 56, or other load beinghandled, to be rolled to a desired position.

In the preferred and illustrated embodiment, the loadengaging element 33on the arm 26 is rotated about the axis of the trunnion pin 48 byoperation of a double acting hydraulic actuator 70. The hydraulicactuator 70 comprises a cylinder element 71 and a cooperating pistonelement 71a having a piston rod 72 extending through one end of thecylinder element 71 and pivotally connected to a lug or crank arm 73 onthe member 58. The other end of the cylinder element 71 is pivotallyconnected by a bolt to an L-shaped frame 75 mounted on the upper side ofthe block 37. The framework 75 comprises a pair of spaced parallelL-shaped plate members 76 extending upwardly from the upper side of theblock 37 and having L portions 77 extending horizontally from the upperends thereof in the direction of the shoes 55. The upper ends of theplates 76 are connected together by a vertical transverse plate 78having a bore for receiving the bolt 74. The framework 75 is movabletogether with the block 37 and the load-engaging element 33 about theaxis of the pins 38, 39. The inner plate 36 is cut away so as to permitthe frame 75 to move therethrough. The load-engaging element 33 and theframework 75 are biased approximately to the limit of their necessarymovement in one direction about the axis of the pins 38, 39 by a spring80 connected between the framework 75, plates 78 and a pin 81 supportedbetween the plates 35 of the clamp arm 26. The upper end of the springis connected to the framework 75 by an eyebolt 82 adjustably connectedto the pin 81 supported between the L portions 77. The bias of thespring 80 is such that the spring tends to move the shoes 55 about thepivot so that the lower ends of the shoes are moved toward the load andthe upper ends of the shoes away from the load. Preferably, the limit ofthe movement of the load-engaging element 33 to which the spring 80urges it is such that when the clamp arms 26 are in their wide-openposition, the shoes 55 will be substantially vertical. As the clamp arm26 is moved about its pivot to move the shoes 55 toward the load, theshoes 55 will, in the absence of engagement with the load, re-

-main in the same, angular position with respect to the clamp arms 26and, therefore, will change their position withrespect to the horizontaland vertical since the clamp arm 26 is swinging about its pivot pin 31.When, however, the shoes 55 engage the load, the lower portion oftheshoes will engage the load first and cause the shoes to .moverelative to the .clamp arm 26 about the axis of the pins 38, 39 topermit the load-engaging faces thereof to align themselves with thesurface of the paper roll to be handled. It can, therefore, be seen thatthe support for the shoes 55 permits rolls of various diameters to behandled by the grab device 12 and yet insures proper engagement of theshoes with the paper roll. Thep ins 38, 39 permit alignment of the shoesabout an axis parallel to the axis of pins 31, while the pins 60 permitthe shoes to rotate about an axis parallel to the length of the roll tocompensate for different radii of curvature of the various rolls. Thespring 80 assures that the shoes 55 will not swing downwardly about theaxis of the pins 38, 39 to a position where the uper ends of the shoeswill engage the load and prevent the aligning movement about the axis ofthe pins 38, 39 from occurring.

The clamp arms 25, 26 have portions 83 extending up wardly from thepivot pins 31, and a fluid pressure actuator 84 including a cylinderelement 85 and cooperating piston 86 is operatively connected beween theupper end portion of the clamp arms. When fluid pressure is supplied tothe clamp side of the hydraulic actuator 84, the upper ends of the clamparms 25, 26 are moved apart to cause the lower ends of the clamp armscarrying the loadengaging elements 33 to move toward each other in aclamping movement and to apply a clamping pressure to a load positionedtherebetween. Application of fluid pressure to the release side of thehydraulic actuator 84 causes the upper ends of the clamp arms 25, 26 tomove toward each other to movethe load-engaging means 33 on each clamparm away from each other.

Fluid pressure is supplied to the actuators 70, 84 from a pump 87carried by the horizontal frame member 27 of the grab. The pump 87 isdriven by a motor 88 and has its suction connected to a reservoir tank89 mounted on the top of the horizontal frame member 27 intermediate thesheaves 28, 29. The pump 87 is provided with conventional pressurerelief means 90. p

The hydraulic system interconnecting the pump, the actuators 70, 84, andthe reservoir is shown schematically in Fig. 8. As shown therein, eachactuatorhas a connection to each side of the piston thereof. Thehydraulic actuator 84 has a conduit 91 connected to cylinder element 85to supply pressure fluid to the clamp side of the piston to cause theupper ends of the clamp arms 25, 26 to move apart and apply a clampingpressure to the load, and a conduit 92 connected to the cylinder element85 on the other or release side of the piston. The supply of fluidpressure to the hydraulic actuator 84 is controlled by a three-positionsolenoid valve 93 having a neutral position wherein its outlet ports areconnected to drain or reservoir return. The solenoid valve 93 has asolenoid 94 for shifting the valve from a neutral position, shown in thedrawings, to the left to connect the conduit 91 with a pressure conduit95 leading from the discharge of the pump 87 and connected to a port ofthe valve, and to connect the conduit 92 with a return conduit 96leading from the valve to the reservoir 89; and a second solenoid 97 forshifting the valve from its other direction from its neutral position toreverse the connections between the conduits 91, 92 on one hand and theconduits 95 96 on the other hand. When the valve 93 is in its neutralposition the con, duits 91, 92 are placed in communication with thereturn conduit 96 by an internal passage in the valve. When the solenoid94 is energized, the pressure supplied to the hydraulic actuator 84through the valve 93 and the conduit 91 causes the actuator to operateto move the clamp arms 25, 26 in a clamp direction and when the solenoid97 is energized, fluid pressure is supplied to the conduit 92 to causethe actuator to move the clamp arms 25, 26 in a release direction.Preferably, the conduit 91 includes a check valve 98 and has anaccumulator 99 in communication therewith at a point intermediate theactuator 84 and the check valve 98. The check valve 98 permits the flowof fluid pressure toward the actuator 84 and normally prevents flow inthe opposite direction. When, however,

pressure is supplied to conduit 92 to cause the actuator 84 to move theclamp arms 25, 26 in a release direction, pressure is also supplied to apiston element 100 of the check valve 98 which operates to lift thevalve element of the check valve from its seat and permit fiow throughthe conduit 91 in a direction away from the actuator 84. The abovedescribed arrangement assures that if power is lost while a load isbeing handled, the pressure on the clamp side of the cylinder will notbe released. The fluid pressure on the clamp side of the piston will betrapped in the actuator 84 and will not be able to flow therefrombecause of the action of the check valve 98. The check valve, however,does not interfere with the normal operation of the actuator 84. p

The side of each of the hydraulic actuators 70, to which pressure issupplied to roll the load in one direction, is connected to one port ofa three-position solenoid valve 103 through a back pressure regulatingmeans 104 by a conduit 105 leading from the actuator 70 to the backpressure regulating means 104 and by a conduit 106 lead ing from theback pressure regulating means 104 to the solenoid valve 103. Similarly,the opposite side of each of the hydraulic actuators 70 is connected toa diiferent port of the solenoid valve 103 through a back pressureregulating means 107 by a conduit 108 leading from the hydraulicactuators 70 to the back pressure regulating means 107 and a conduit 109connecting the back pressure regulating means 107 and the solenoid valve103. The solenoid valve 103 is similar to the solenoid valve 93 andincludes a solenoid 110 which, when energized, moves the solenoid valvefrom a neutral position to a position wherein the conduit 106 isconnected to a pressure conduit 111, which is, in turn, connected withthe pressure conduit 95, and wherein the conduit 109 is connected to areturn conduit 112. The valve 103 also includes a solenoid 113 whichshifts the solenoid valve 103 in its other direction from its neutralposition to connect the conduit 106 with the return conduit 112 and theconduit 109 with the pressure conduit 111. When pressure is supplied tothe conduit 106, the hydraulic actuators 70 roll the load in onedirection, and when supplied to the conduit 109, the actuators roll theload in the opposite direction.

The back pressure regulating means 104, 107 permit unimpeded flow fromthe solenoid valve 103 to the actuators 70, but permit flow from theactuators 70 only when a predetermined pressure is exceeded in the lines105, 108, respectively. To this end, the back pressure regulating means104 includes a connection 114 between the conduits 106, 105, having acheck valve 115 therein that permits flow to the actuator 70 butprevents flow in the opposite direction. A pressure differential valve116 is connected in parallel with the check valve 115 and permits flowbetween the conduit 105 and conduit 106 in a direction away from theactuator 70 when the pressure in the conduit 105 exceeds the pressure inthe conduit 106 by a predetermined amount. The back pressure regulatingmeans 107 is the same, in the illustrated embodiment, as the backpressure regulating means 104 and includes a check valve 117 whichpermits unimpeded flow to the actuator 70 through the conduits 108, 109,and a pressure differential valve 118 which permits flow from theactuator 70 through the conduit 108 to the conduit 109 only when thepressure in the former exceeds the pressure in the latter by apredetermined amount. The above-described system assures that pressurefluid will always be trapped on the opposite sides of the pistons of theactuators 70 and will enable the load to be rolled to a particularposition and held therein since the pistons will be unable to move inabsence of a pressure applied thereto directly from the pump 87. In theevent of a power failure, the pressure fluid trapped in the actuators 70assures that the load will also be held in its immediate position.

' A flow control valve 120 is preferably included in the conduit 111.This valve limits the amount of fluid flowing into line 111 and protectsagainst detrimental drop in the pressure to the actuator 84 when theactuators 70 are operated.

The material manipulating device described is extremely flexible in.that other types of load-engaging elements may be readily substitutedfor those shown by simply removing the pins 38, 39. This is done byfirst detaching the keeper plates 44 and then pulling the pins 38, 39.When this is done, the block 37, the framework 75 and actuator 70, andthe shoes 55 will be movable as a unit and a new unit can be easilysubstituted. Similarly, different shoes 55 maybe put on the elements 33by pulling the pins 60. i From the foregoing description, it can be seenthat the present invention provides a material handling apparatus havingload-engaging elements supported on one end of pivoted clamp arms forself-aligning movement about an axis perpendicular to the plane ofmovement of the clamp arms and about an axis parallel to the plane ofmovement of the clamp arms. The load-engaging elements are preferablyrotatable with respect to the clamp arms by power actuated means and areurged about their axes perpendicular to the plane of movement of theclamp arms to a position which will assure that the load-engagingelements will be able to properly align themselves upon engagement withthe load. The clamp arms are moved about their pivots and theload-engaging elements are rotated about their axes by fluid pressureactuators which are connected into a fluid under pressure and returnsystem which is so constructed and arranged that a pressure is alwaysmaintained in the clamp arm actuator for moving the clamp arms in aclamp direction and pressure is also always maintained on both sides ofthe pistons of the actuators for rotating or rolling the load-engagingelements. Preferably, the pump for supplying fluid under pressure andthe return reservoir are carried by the grab.

While the preferred form of the invention has been described inconsiderable detail, it will be apparent that the invention is notlimited to the construction shown or the uses referred to, and it is myintention to cover hereby all adaptations, modifications and changeswhich come within the practice of those skilled in the art to which theinvention relates and the scope of the appended claims.

Having thus described our invention, we claim:

1. In a material handling apparatus including an overhead supportmember, a material manipulating grab, and means suspending said grabfrom said support member and operable to raise and lower said grab, saidgrab comprising a generally horizontal frame member, first and secondgenerally vertical clamp arms pivoted to said frame member for movementin a first vertical plane about parallel first axes, power-actuatedmeans operatively connected to said arms for moving said arms about saidaxes, first and second load-engaging elements adapted to engage oppositevertical sides of a load and each having a load-engaging position inwhich the element is disposed in a generally vertical plane normal tosaid first vertical plane and in which position the element is supportedfor rotation about a roll-over axis through the element and normal tothe plane thereof and for rotation about a selfaligning axis parallel tosaid first axes and normal to said roll-over axis, first and secondconnecting means respectively connecting said first and second elementsto corresponding ends of said first and second clamp arms respectively,each of said connecting means comprising a first member connected to thecorresponding clamp arm for rotation about said self-aligning axis whenthe element is in said load-engaging position and a second membercarried by said first member for rotation about said roll-over axis whenthe element is in said load-engaging position, said second member ofeach connecting means carrying the respective load-engaging element,means carried ,by ach of .saidarms and limiting the movement of themember of the connecting means associated with the arm which isrotatable about the self-aligning axis of the connecting means, andpower-actuated means carried by at least one of said arms andoperatively connected to the member of the connecting means associatedwith the arm which is rotatable about said roll-over axis for rotatingthe member, the members of said connecting means rotatable about saidself-aligning axis each being biased to a predetermined position aboutits axis.

2. In a material handling apparatus including an overhead supportmember, a material manipulating grab, and means suspending said grabfrom said support member and operable to raise and lower said grab, saidgrab comprising a generally horizontal frame member, first and secondgenerally vertical clamp arms pivoted to said frame member for movementin a first vertical plane about parallel first axes, power-actuatedmeans operatively connected to said arms for moving said arms about saidaxes, first and second load-engaging elements adapted to engage oppositevertical sides of a load and each having a load-engaging position inwhich the element is disposed in a generally vertical plane normal tosaid first vertical plane and in which position the element is supportedfor rotation about a roll-over axis through the element and normal tothe plane thereof and for rotation about a self-aligning axis parallelto said first axes and normal to said roll-over axis, first and secondconnecting means respectively connecting said first and second elementsto corresponding ends of said first and second clamp arms respectively,each of said connecting means comprising a first member connected to thecorresponding clamp arm for rotation about said self-aligning axis whenthe element is in said load-engaging position and a second membercarried by said first member for rotation about said roll-over axis whenthe element is in said load-engaging position, said second member ofeach connecting means carrying the respective load-engaging element, aspring carried by each of said arms and operatively connected to themember of the connecting means associated with the arm which isrotatable about the selfaligning axis of said connecting means toyieldably hold the member in a predetermined load-engaging position withrespect to said member, and power-actuated means carried by at least oneof said arms and operatively connected to the member of the connectingmeans associated with the arm which is rotatable about said roll-overaxis for rotating the member.

3. In a material handling apparatus including an overhead supportmember, a material manipulating grab, and means suspending said grabfrom said support member and operable to raise and lower said grab, saidgrab comprising a generally horizontal frame member, first and secondgenerally vertical clamp arms pivoted to said frame member for movementin a first vertical plane about parallel first axes, power-actuatedmeans operatively connected to said arms for moving said arms about saidaxes, first and second load-engaging elements adapted to engage oppositevertical sides of a load and each having a load-engaging position inwhich the element is disposed in a generally vertical plane normal tosaid first vertical plane and in which position the element is supportedfor rotation about a roll-over axis through the element and normal tothe plane thereof and for rotation about a self-aligning axis parallelto said first axes and normal to the roll-over axis, first and secondconnecting means respectively connecting said first and second elementsto corresponding ends of said first and second clamp arms respectively,each of said connecting means comprising a first member connected to thecorresponding clamp arm for rotation about said self-aligning axis whenthe element is in said load-engaging position anda second member carriedby said first member for rotation about said roll-over axis when theelement is in said loadengaging position, said second member of eachconnectns m a y g the respective load-engaging element,

and power-actuated means carried by at least one of said arms andoperatively connected to the member of the corresponding connectingmeans rotatable about said roll-over axis for rotating the member, aspring carried by each arm and operatively connected to the member ofthe connecting means associated with the arm that is rotatable about theself-aligning axis to bias the member to a predetermined position aboutits axis which positions the corresponding element in a position whichcorresponds approximately to its said load-engaging position when amaximum width load is engaged and being handled by said elements.

References Cited in the file of this patent UNITED STATES PATENTS WehrMay 26, 1931 Clay Sept. 27, 1949 Acton Nov. 20, 1951 Frischmann May 13,1952 Halgren et al. Mar. 11, 1952 Frischmann July 22, 1952 Tucker Nov.18, 1952 Sherriff Aug. 4, 1953 Sherritf July 13, 1954

